Yes and no, but most of what the PT has said makes sense and would lead to some real positional problems going overhead. From this, I wouldn't say your PT identified your lats as being the limiting factor, either. According to this report, there are two big things that will cause you to hyperextend your back when going overhead: 1. limited hip extensibility. if you can completely open the hip joint, your "neutral" position will involve a forward tilting pelvis. This in turn forces extension of the lumbar. I've had a similar problem myself. Increase mobility so you can fully open up the hip, and your pelvis can sit in a true neutral position. This stretch is your best friend for improving that hip extensibility: (note, the guy in this video has pretty crappy form, ideally, the back knee should be completely against the wall) http://www.google.com.hk/url?sa=t&r...xYGYAQ&usg=AFQjCNHNSxKb8TcZV9A2qSgAoIWbxPdeUg 2. pelvo-lumbar stability. basically, PT thinks you've got a weak core. if this is in fact the case, it will make lumbar hyperextension more likely when going overhead with anything heavy. a good test for whether or not this is what is causing your problem: can you get into a good overhead position with an unweighted bar? if the problem exists even without putting anything heavy overhead, it's more likely a mobility issue than a strength issue. Worth noting is that the PT doesn't actually mention anything here that suggests shoulder mobility as preventing you from getting into a good overhead. Obviously this isn't dispositive. In the pic you posted it didn't look like you could get your shoulder into a proper overhead position, but it's hard to say from one pic. Try some pass-throughs and shoulder dislocates. They may help. My gut from all of this, though, is that the hip mobility problem is the big one. Fix that and I think everything will look a lot better.